The present invention relates to the field of moulding three-dimensional products from a mass of foodstuff which is suitable for human consumption. In particular, the invention relates to the production of moulded portions of a foodstuff starting from a mass of the foodstuff in question, which mass is of substantially pasty, pulpy consistency. The invention relates in particular to the moulding of edible products from a mass which predominantly comprises pounded meat, in particular chicken or other poultry meat, but also beef, pork, etc. The invention also relates to the moulding of products from fish, dough, etc.
With regard to the processing of poultry meat, the invention is based on the recognition that the processing of poultry produces low-quality meat, for example meat which has been mechanically removed from the bone and meat trimmings, which can be given a higher added value by being upgraded. Also, there is an increasing consumer demand for xe2x80x9cmoulded meat productsxe2x80x9d, for example for snacks, and for meat products with an attractive appearance. In these sectors, demand may change quickly, so that it must be possible to adapt the production method according to the invention quickly to meet demand. Furthermore, it is observed that the demand for moulded (meat) products is very high, and consequently it must be possible to achieve a high production capacity.
Various methods and moulding machines are known for moulding products from a (meat) mass, and a number of these methods and moulding machines will be described briefly below.
U.S. Pat. No. 4,987,643 has described a moulding machine of the xe2x80x9cslide-platexe2x80x9d type, for the purpose of producing portions of hamburger meat. A machine of this nature has a substantially planar moulding plate containing a plurality of mould cavities for the meat mass. The moulding plate can be moved to and fro substantially in its horizontal plane for the purpose of displacing the mould cavities between a filling position, in which the mould cavities are filled with meat mass which has been placed under pressure by a meat pump, and a removal position, in which the moulded meat products are removed from the mould cavity. The capacity of a slide-plate machine of this nature is limited in particular by the rate at which the mould plate can be moved to and fro; it is necessary for the mould plate of the known machine to come to a standstill at the filling and removal positions. The speed of movement of the mould plate is limited by the inertia forces which are generated by the heavy mould plate which is moving to and fro and the components which are connected thereto. The reciprocating movement is partly limited by the fact that the mass which is introduced into the mould cavity under a filling pressure has to remain in the closed mould cavity for a certain period in order to obtain the desired cohesion or adhesion of the pieces of meat. The design of these known moulding machines of the slide-plate type has proven unsuitable or, at any rate, disadvantageous for further increasing the production capacity, which would be desirable in view of the increasing demand for moulded meat products.
Another known type of moulding machine for meat products and the like is the xe2x80x9cturret-typexe2x80x9d, an example of which is described in U.S. Pat. No. 4,193,167. In this type of moulding machine, the mould cavities are arranged on a horizontal rotating wheel which can be rotated about a vertical axle. The mould cavities have an opening on the underside of the rotary wheel, so that the mould cavities extend parallel to the axis of rotation of the rotary wheel. Opposite the opening of the mould cavity, this known moulding machine has a mechanically displaceable base, the movement of the base being derived, via a cam-disc mechanism, from the rotation of the rotary wheel. The operation of the associated filling device is synchronized with respect to the rotation of the rotary wheel. In this known moulding machine, the large number of and interaction between the moving components again limits the extent to which the capacity can be increased. Particularly when removing the moulded products, the adhesion of the meat mass to the side wall and the base of the mould cavity represents a problem for operating with success at high speed. The way in which the mould cavities are filled in this known machine also limits the production capacity.
Another type of moulding machine for moulding three-dimensional products from a meat mass or the like is the xe2x80x9crotating drum typexe2x80x9d. Known moulding machines of this type have a rotatable drum which is driven in continuous rotation by an associated drive, with a plurality of mould cavities on the outside of the drum, which cavities, in a filling position, move past a filling component which is arranged along the outside of the drum and by means of which the mould cavities are filled with (meat) mass. In a removal position, which is located further on in the direction of rotation of the drum, the moulded meat products are driven out of the mould cavities. In this type of machine, the mould cavities are located transversely with respect to the axis of rotation of the drum.
Examples of known moulding machines of the xe2x80x9crotating drum typexe2x80x9d are described in U.S. Pat. Nos. 3,504,639, 3,851,355, 4,212,609, GB 2,259,043, FR 2,491,734 and FR 2,538,223. The development of the moulding machine of this xe2x80x9crotating drum typexe2x80x9d is currently not sufficiently advanced for achieving the production capacity required both currently and in the future, and consequently the abovementioned slide-plate moulding machines have the highest capacity and are used for mass production.
In the following text, it is assumed that a filling pressure is exerted on the (meat) mass which is to be introduced into the mould cavity in order to fill the mould cavity with a portion of the mass. Therefore, the filling pressure is the pressure which is exerted on the (meat) mass while the mould cavity is being filled.
In order to ensure that the (meat) pieces of which the mass consists adhere to one another, thus producing a dimensionally stable product, after the mould cavity has been filled with the (meat) mass, the mass has to be subjected to a fixing pressure for a fixing period which takes place at some point between the time at which the mould cavity is filled and the time at which the moulded product is removed and during which period the portion of the mass is enclosed in the mould cavity. After the fixing period, an edible product which forms a cohesive unit in a three-dimensional shape is obtained, which product can then be removed from the mould cavity.
In known moulding machines, such as for example the moulding machine which is described in EP 0,447,003, a portion of the mass is pressed into the open mould cavity by the filling component under a filling pressure. Then, the mould cavity is closed by the fact that the moulding plate with its mould-cavity opening slides away from under the opening of the filling component and moves under a closed top plate. Inevitable leakage from the mould cavity and/or relaxation of the mass in the mould cavity indicates that the pressure of the mass in the mould cavity falls slightly after the cavity has been closed. In the context of the present application, the pressure which then prevails in the closed mould cavity is regarded as being the fixing pressure. This fixing pressure remains present during the displacement of the mould plate until the mould cavity reaches the opening in the bottom plate, with the result that the mould cavity is opened to atmosphere. In this known moulding machine, the fixing pressure is therefore directly and exclusively related to the filling pressure, and it is impossible to control the fixing pressure independently of the filling pressure. Also, the duration of the filling period and the fixing period cannot be influenced independently of one another, since they are both determined by the displacement speed of the moulding plate of the moulding machine. A final drawback is that as soon as the opening in the bottom plate is reached, the mass in the mould cavity, which is still under pressure, immediately seeks to escape from the opening which is increasing in size, and this has an adverse effect on the shape of the product.
One object of the invention is to provide measures which lead to a treatment of the mass when producing the edible products which is technologically optimum with regard to the (meat) mass which is to be processed.
A particular object of the invention is to provide measures which make it possible to control the fixing pressure largely, or preferably completely, independently of the filling pressure. As has been stated, the fixing pressure is one of the principal parameters of the moulding process. By providing devices which allow the fixing pressure to be controlled in this way, it is possible to optimally adapt the operation of each of the said devices to the (meat) mass which is to be processed by the device in question. Thus, there will be an optimum formula for each mass which is to be processed in order to mould products therefrom, and the perimeters of the formula will in principle comprise the time, the pressure and generally also the temperature. In known moulding methods, additives are often added to the edible mass which is to be processed in order in this way to allow the moulding process to proceed as desired, but this increases the cost price, and furthermore such additions are often deprecated by the consumer. For example, if an excessively high (filling and/or fixing) pressure is used or if a pressure is maintained on a (meat) mass for an excessively long period, there is a risk of fat and/or moisture being pressed out and/or of the components which form the mass becoming segregated. Furthermore, high pressures on the edible mass lead to design problems in the devices, such as at the seal which is required for the filling component.
It should be noted that the operation of filling the mould cavities, in particular the time involved in filling the mould cavities, is largely dependent on the filling pressure exerted on the mass. Independence of the filling pressure and fixing pressure allows the filling and moulding process to be set up optimally, partly with a view to achieving a high capacity of the device.
Furthermore, the methods and devices according to the invention make it possible to process numerous different masses, with the emphasis falling on the processing of meat masses.
A further object of the invention is to minimize the filling pressure. For example, in the method provided according to the invention, the filling pressure in the case of pounded meat is between 0.2 and 5 bar, and the fixing pressure is between 1 and 15 bar.
A further object of the invention is to provide measures which make it possible to reduce the mechanical load on the (meat) mass when a mould cavity is being filled compared to that which is employed in known moulding machines. This mechanical load is caused in particular by the filling pressure and by shear forces which are exerted on the meat mass, for example, when a stripper moves past the opening of the filled mould cavity. Excessive load on the meat mass damages the structure of the meat and therefore reduces the quality of the product. Furthermore, the shear forces exerted when a stripper of the like moves past may cause an undesirable change in the texture of the product.
A further object of the invention is to propose measures which make it possible to produce three-dimensionally moulded foodstuffs for human consumption with a high capacity. A particular object of the invention is to allow the moulding of the products to take place as far as possible in a continuous process, in which the mould cavities move along their path at a substantially constant speed and the filling and emptying of the mould cavities take place as far as possible on a continuous basis. A particular object of the invention is for the moulded products to be removed from the mould cavities without using mechanical ejectors, or with only minimal use of such ejectors.
Another object of the invention is to provide solutions for controlling the influence of the viscosity and other relevant properties of the (meat) mass which is to be fed to the mould cavities on the moulding of the product in the mould cavity. In particular, the invention provides for the preparation of the (meat) mass supplied in a continuous process, during which the (meat) mass can, for example, be cooled or heated and additives, such as water, spices, colorants and flavourings, egg whites, can be added.
Another object of the invention is to propose measures which make it possible to arrange differently shaped mould cavities on a moulding machine in a simple manner and in a short time, preferably without having to adapt the filling and/or removal system of the moulding machine. The invention also aims to make it possible to produce products of different shapes at the same time using a single moulding machine.
A further object of the invention is to propose measures which ensure a high level of hygiene during moulding of the products.
Another object of the invention is to propose measures for producing foodstuffs with a product body which is composed of a plurality of parts. This description encompasses, inter alia, layered products, products with an internal filling, etc.
A further object of the invention is to provide measures which allow the outside of the products to be treated, for example by the arrangement of a ribbed or grid pattern.
The invention also aims to provide a compact device.
A further object of the invention is to provide measures which allow the moulded products to be packaged efficiently.
The invention provides an improved method for moulding three-dimensional products from a mass of foodstuff which is suitable for human consumption, comprising the steps of:
filling a mould cavity with a portion of the mass via a filling opening which is associated with the mould cavity, under the influence of a filling pressure which is exerted on the mass and for a filling period,
closing the filling opening of the mould cavity,
holding the mass in the closed mould cavity for a fixing period,
opening the mould cavity and removing the moulded product.
The improvement comprises the use of fixing-pressure-exerting means, which are designed to exert a fixing pressure which acts on the mass in the mould cavity after the filled mould cavity has been closed.
The invention furthermore provides devices for carrying out the method and other devices for moulding three dimensional products from a mass of foodstuff.